The gun in question is modelled after the real New Model Navy of 1863. The 6-1/2" barrelled guns by Pietta are technically inaccurate reproductions of the New Model Belt revolver. The frames of the NMB were smaller than the Army and Navy but still were .36 caliber and six shots. For economies sake, Pietta makes it on the one frame and calls it the Navy, Police and Belt, whatever.